The funds are revenues above and beyond what was expected for the 2018 budget, according to Kurt Weiss, spokesperson for the Michigan State Budget Office. The Line 5 tunnel request is a fraction of the $630 million supplemental spending plan sent to lawmakers Nov. 14.

The outgoing governor called it a "common-sense solution" to safeguard the Straits from an oil spill while maintaining the pipeline connection.

"The taxpayers of Michigan will benefit greatly from this project but won't have to pay for it," Snyder said in a statement at the time.

Plans call for pipeline owner Enbridge Energy to fund the construction and design of the tunnel -- a bill estimated between $350 million to $500 million.

Once completed, Snyder wants the Mackinac Bridge Authority to assume ownership of the tunnel.

Many of those details are still under discussion, with Snyder wanting to finalize them before his term ends and Governor-elect Gretchen Whitmer takes over on Jan. 1. During her campaign, Whitmer criticized the tunnel plan and said she wanted to shut down Line 5.

Weiss contended that Snyder wasn't reneging on his promise of a tunnel with no cost to taxpayers.

Enbridge will still bear the full cost of construction and design, which is different from necessary state oversight of the large-scale tunnel project, he said.

"This money is really for the oversight of Enbridge, if you will, and the administration to make sure the project is managed to the state's satisfaction," Weiss said.

Michigan Department of Natural Resources Director Keith Creagh said the funds will ensure that the "highest safety standards as possible" are met, that Enbridge achieves performance criteria and milestones and that the state has independence in their oversight.

"We've always been very specific saying the construction, maintenance and operations of the tunnel" will be footed by Enbridge, Creagh said.

If all goes to plan, the tunnel will be operational sometime between 2025 and 2028. The 65-year-old twin pipelines would be decommissioned only after the tunnel is completed.

It's possible the state will need more or less than $4.5 million for tunnel oversight activities, Weiss said. That'll be reassessed after construction is underway.

Creagh said some of the funds could be used to fight legal suits against the tunnel.

Some environmental groups raised concerns about the appropriation, in conjunction with their ongoing opposition to parts of the tunnel plan.

"Using public funds for Canadian oil company Enbridge Energy's risky Line 5 tunnel, especially after state officials promised no taxpayer dollars would go toward a tunnel, is irresponsible and would keep oil pumping through the damaged Line 5 Pipeline for another 10 years or more," Lisa Wozniak, executive director of Michigan League of Conservation Voters, said in a statement.

Wozniak called the tunnel a "false solution" that would keep the Great Lakes at risk of an oil spill.

Sean Hammond, deputy policy director at the Michigan Environmental Council, said in a conference call Monday morning, Nov. 26, that his organization has concerns about giving tunnel oversight to the Mackinac Bridge Authority board, whose members are not elected but appointed by governors.

Currently, Snyder's appointees hold a majority on the seven-member board.

Hammond said the organization has additional concerns about the proposed $4.5 million appropriation and the lack of a definite timeline on decommissioning Line 5.

"This pipeline is already 65 years old," Hammond said. "We know there's coating holes and other issues. We really have concerns with the way the agreement is taking shape at this point."

Enbridge and the bridge authority must still agree to numerous details, including those about construction, maintenance and who pays for minor and major malfunctions of the tunnel infrastructure.

Creagh said state department representatives are working out those details. Once complete, they'll be presented to the board for discussions and approval.

The board is also awaiting a finalized agreement between Enbridge and the state, as well as action on state legislation introduced this month that would allow the authority to take ownership of the tunnel.

Mackinac Bridge Authority Board Chairman Patrick "Shorty" Gleason said the board will likely need more time than the end of December to negotiate and discuss any agreement, the Associated Press reported Nov. 24.

The Line 5 pipeline, built in 1953, runs 645 miles from Superior, Wisconsin, to Sarnia, Canada, and transports up to 540,000 barrels of light crude oil and natural gas liquids per day.

A worst-case scenario oil spill in the Straits of Mackinac could have an economic impact in the tens of billions of dollars, according to a recent study commissioned by an advocacy group and conducted by a Michigan State University professor.

Calls to shutdown the pipeline were renewed earlier this year, when an anchor struck it on April 1. The line was damaged with three dents and an abrasion but has since been patched up with composite sleeves.

Lawmakers still need to approve the $4.5 million request. If they do, it'll happen before Christmas, Weiss said.

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